This invention relates to a moving object detecting device for detecting an object moving in a supervisory zone by radiating over the zone such continuous energy waves as ultrasonic waves, microwaves or the like, and detecting frequency deviation of reflected waves from the object caused by its movement.
1. Disclosure of the Prior Art
Generally, the moving object detecting devices of the kind referred to are arranged for keeping such continuous energy waves as ultrasonic waves, microwaves or the like of a predetermined frequency radiated over the supervisory zone, and detecting the frequency deviation in the reflected waves caused as the Doppler effect in response to the movement of the object present in the supervisory zone.
In U.S. Pat. No. 4,287,579 to H. Inoue et al, assigned to the same assignee as in the present case, there has been disclosed a moving object detecting device forming an earlier invention of the present invention. In this device of Inoue et al, ultrasonic waves are radiated from a wave radiator to the supervisory zone, the reflected waves from any object present in the zone are received by a wave receiver and converted into electric signals, and such electric signals are further converted into a pair of intermediate signals (beat signals). The device is arranged so that the pair of the intermediate signals are converted to binary axial code signals corresponding to the polarity of the intermediate signals, a logic sum of the pair of the intermediate signals is taken to discriminate the presence of the object within the supervisory zone, a detection is made to determine in which one of quadrants of vector plane having the intermediate signals as its basic axes the reflected waves from the object are present, positional shift in the quadrants as well as moving direction of the object are detected, and these information detected on the object are indicated by means of any proper indicating means.
In the foregoing device of Inoue et al, however, the presence of the moving object is. to be discriminated by means of, so to say, a time for which the object moves continuously in a fixed direction, and there has arisen such a problem that a presence in the supervisory zone of such a slowly moving but inherently stationary article as a curtain which swings would cause an object's shift detecting means actuated to provide signals responsive to swinging direction and the like even though the article has practically made no substantial shift from the viewpoint of shifting distance, and a malfunction of the device has been thereby caused to occur. In an event when such malfunction is attempted to be avoided by inserting, in the device at a stage preceding the indicating means, such time constant means as an integrating means so as to prolong the time constant, there arise another problem that any object which rapidly moves within the supervisory zone can be no more detected.
2. Field of Art
It is the primary object of the present invention, therefore, to provide a moving object detecting device capable of detecting the presence of a moving object within the supervisory zone exactly and at a high precision, irrespective of its moving velocity.
According to the present invention, this object is attained by a moving object detecting device arranged so that an output of an oscillating means which oscillates at a predetermined frequency is provided to a wave radiator for radiating in a supervisory zone continuous energy waves, reflected waves of said continuous energy back from an object present in the supervisory zone are made incident on a wave receiver, a received-wave signal from said wave receiver is converted by a converter into a pair of intermediate signals forming basic axes of a vector plane, positional shift and moving direction of the object on said vector plane are detected by a detecting means, and thereby detected information of the moving object is made acknowledgeable by an indicating means, characterized in that an angle of the received-wave signal at every moment with respect to said basic axes in the vector plane is detected in time series by an angle detecting means, any angular difference at respective moments is operated by an operating means and, when a predetermined level of said difference is detected, a signal processing means provides an object detection signal to a detection indicating means.
With the moving object detecting device of such arrangement as above of the present invention, it is made possible to detect the moving object present in the supervisory zone highly precisely, irrespective of moving velocity of the object, by detecting in time series an angular deviation information of the moving object from the pair of intermediate signals obtained, in particular, through a conversion of energy deviation components of the received-wave signal.
Other objects and advantages of the present invention should be made clear in following description of the invention detailed with reference to preferred embodiments of the invention shown in accompanying drawings.